1. FIELD OF THE INVENTION
The invention relates to a control device for a wiper apparatus which has a two-direction rotatable motor for making wipers reciprocatingly wipe, for example, the rear or front windshield of an automobile, etc.
2. DESCRIPTION OF THE RELATED ART
A conventional wiper apparatus comprising a rise-up mechanism has been suggested (U.S. Pat. No. 4,599,546). The rise-up mechanism is defined as one used with a wiper apparatus for wiping the windshield surface in which upon turning off a wiper operation switch, the wiper blade is lowered below the lower limit of the wiping range thereof. This rise-up mechanism is used as a device for accomodating the wiper blade under a bonnet when not in wiping operation.
In the wiper apparatus disclosed by U.S. Pat. No. 4,599,546, a wiper motor is controlled to reciprocate the wiper blade by being driven in forward and reverse directions reciprocally within a predetermined angular range, thereby realizing a mechanism capable of the rise-up operation.
The above-mentioned prior art apparatus, in which forward and reverse operation is controlled by complicated mechanical switches, is complex in construction. The U.S. Pat. No. 4,309,646, on the other hand, discloses an apparatus in which such a mechanical means is replaced by an electronic circuit to overcome the above-described disadvantage.
The apparatus of U.S. Pat. No. 4,309,646, however, requires a complicated position detector for detecting the position of the wiper blade. Even if a comparatively simple cam device configured electrically is used in the apparatus, it is necessary to provide a conductive part movable with the wiper motor, three brushes slidable on the conductive part, and a connector for applying a source voltage to the conductive part. Normally, the connector is also constructed of a brush, and therefore the position detector is required to include four brushes. The electric cam device of this type, however, is arranged in a limited small space in the wiper motor, and therefore, in the case where the number of brushes is high, the wiper motor becomes bulky consequently or the brushes cannot be arranged in the motor for lack of ample space.